URANS and Reynolds stress

sharonyue · July 12, 2021, 23:19

Hello guys, regarding the Reynolds stress, we have the following ways to calculate it in OpenFOAM:

1) for LES, we can obtain the resolved Reynolds stress by UPrime2Mean.
2) for RANS, we can obtain the Reynolds stress by postProcess -R function.

But what about URANS? Is it identical with RANS? Lets take the flow over cylinder as an example, in such flows, R is also periodic, In order to obtain averaged Reynolds stress, we also need to calculate time-averaged R?

dlahaye · July 13, 2021, 06:18

Affermative, yes, true, the tensor R at every time step is a Reynolds averaged quantity.

July 12, 2021, 23:19	URANS and Reynolds stress	#1
sharonyue Senior Member Dongyue Li Join Date: Jun 2012 Location: Beijing, China Posts: 840 Rep Power: 17	Hello guys, regarding the Reynolds stress, we have the following ways to calculate it in OpenFOAM: 1) for LES, we can obtain the resolved Reynolds stress by UPrime2Mean. 2) for RANS, we can obtain the Reynolds stress by postProcess -R function. But what about URANS? Is it identical with RANS? Lets take the flow over cylinder as an example, in such flows, R is also periodic, In order to obtain averaged Reynolds stress, we also need to calculate time-averaged R? __________________ My OpenFOAM algorithm website: http://dyfluid.com By far the largest Chinese CFD-based forum: http://www.cfd-china.com/category/6/openfoam We provide lots of clusters to Chinese customers, and we are considering to do business overseas: http://dyfluid.com/DMCmodel.html

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July 13, 2021, 06:18		#2
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 735 Blog Entries: 1 Rep Power: 17	Affermative, yes, true, the tensor R at every time step is a Reynolds averaged quantity.